The present invention relates to a method for forming a socketed tube with a thickened end, provided with a circular inner groove, by deforming the tube which has been brought into a deformable condition by applying heat.
Such a method is known per se. According to this known method during the extrusion of a tube, the discharge rate of the tube is reduced such that, in a part thereof, a greater wall thickness is produced. This part of the tube with a thickened wall is thereupon, by a separate operation, provided with a socket end and a groove. The formation of the tube part with thickened wall during extrusion is, however, attended with the drawback that it cannot be assured that the wall thickening meets well defined conditions.